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  <title>Document</title>
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<body>
  <p>jQuery callbacks</p>
  <script src="https://cdn.bootcss.com/jquery/3.3.1/jquery.js"></script>
  <script>
    // observer 一对多
    var callbacks = $.Callbacks() //注意大小写
    callbacks.add(function (info) {
      console.log('fn1', info)
    })
    callbacks.add(function (info) {
      console.log('fn2', info)
    })
    callbacks.add(function(info) {
      console.log('fn3', info)
    })
    
    callbacks.fire('gogogo')
    callbacks.fire('fire')
  </script>
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